The electrocatalytic activities of metals for the small molecule reactant of COィイD22ィエD2 were investigated by in-situ infrared spectroscopy. The various products were formed from COィイD22ィエD2, such as CO, formate, methane, ethylene, and alcohols, etc. in aqueous solutions. Distributions of products are depended on electrode metals.Two electron reductive products, CO and formate are produced first, then hydrocarbons are produced from CO. Oxalate was formed in stead of formate in non-aqueous media.1. The selectivity of CO/oxalate was investigated in non-aqueous solution. Active electeodes, such as Au, produce CO and inactive electrodes, such as Pb, produce oxalate. While, Pt, an active electrode, produces mainly oxalate. (1) Infrared spectroscopy revealed the surface of Pt was fully covered in the course of COィイD22ィエD2 reduction with CO, which would prevent adsorption of COィイD22ィエD2-anion redical, intermediate.2. Hydrocarbons are main products on Cu electeodes. The distributions of hydroc
… Morearbons depend on the orientation of Cu single crystal electrodes. Methane is mainly formed at (111) surface, while ethylene is mainly formed at (100) surface. Adsorbed CO, intermediate to hydrocarbons, is investigated on various surfaces of Cu single crystal electrodes by infrared spectroscopy. (1) Different types of CO adsorbed on Cu electrodes were observed and assigned. The infrared band at 2050 cmィイD1-1ィエD1 is assigned to CO adsorbed on (100) terrace and the band at 2075 cmィイD1-1ィエD1 is to that at (100) step and/or at (111) step. CO adsorbs on (111) terrace and expresses the reductive reactions but shows no infrared bands. CO adsorbed on (111) may be infrared inactive, for example, adsorbed parallel to the metal surface. (2) Different types of CO adsorption would contribute different distributions of hydrocarbon products on various surfaces.2.炭化水素の選択性 Cu電極への吸着COについて赤外分光法で検討した。Cuは炭化水素生成に高活性であり,(111)面ではメタンが,(100)面ではエチレンが主に生成する。(111)と(100)の基本指数面およびこれらのステップとテラスからなる一連のCu単結晶電極を作成し,COの吸着状態を調べた。(1)複数のCO吸着型の存在を示し、その帰属を明らかにした。2050cm^<-1> ; (100)テラス面上のon-top型CO。2075cm^<-1> ; (100)ステップあるいは(111)ステップに吸着したon-top CO。赤外不活性CO ; (111)テラスに吸着したCO,試験的に電極面に平行に吸着COに帰属。(2)炭化水素生成選択性の異なる電極面に,異なったCO吸着種が存在することを明らかにした。 Less